It depends if he is nice to me. I'm not a girl, but I suppose that girls can be rude too. If she is nice to me and rude to everyone else, I would still chat with her. I see no reason not to. Otherwise... not. ;)

He always wanted to talk rude things and want to make love online. We always argue coz i dont want to do it online. but the sad part is i've fallen inlove to this strange guy, whom i havent seen even on cam. I only seen him on pictures.:(
Will i still believe that he loves me? He said he loves and lust at me.And he wanted to marry me, can this be possible? or i will just avoid him, which is so difficult for me now.

nope! if they turn rude/crude i give them one warning. i tell them that i am not interested in chatting with someone about that topic. (or something to that effect)
if they persist after that, then i send a message saying sorry but your not the type of guy i thought you were, and then block them.
dont feel bad about blocking ppl. it is they who should feel bad that they offended you to the point of not wanting any contact with them at all.